Communication in Times of Crisis: The Preppers’ Hidden Mesh Network
An independent, airborne radio network bypassing the internet. I dove into the tech and the choice between Meshcore and Meshtastic.
By Brian Poulsen | March 2026
The Unknown Network
The other day, I was scrolling down my feed when I stumbled upon a post that made me stop in my tracks. It was written for the “electronics nerds” and was about building a network where you can communicate electronically completely without the power grid, without the internet, and allegedly entirely without mobile phones. That last part later turned out to be a bit of a technical stretch, but I didn’t know that yet.
In a time when we are totally dependent on the cell towers, routers, and underground cables always working, it sounded wild that a bunch of volunteers are currently connecting the country with what appears to be small radios.
The post talked about things I had never heard of before. A network called Meshcore. Small, cheap devices that people were encouraged to hide up under their roof tiles, which can magically send encrypted text messages several kilometers through the air. They simply forward the messages for each other in a large, invisible web. No license, no subscription, and no bills from a telecom company. Just an independent, parallel internet being built at this very moment.
I understood jack about the technology itself. My knowledge of radio communication roughly stopped at the stationary walkie-talkie I had in my childhood bedroom in the early 90s, where a massive antenna on the gable of the house let me talk to friends in the neighborhood. But the very thought in this post still hit me like a punch to the gut.
Just think about it. Right outside your window, there’s highly likely an invisible communication network floating over the city roofs. A network that your neighbor might already be connected to, while the rest of us walk around clueless and a hundred percent dependent on the telecom companies’ infrastructure not blacking out.
I simply had to find out what this underground world was all about. Not because I had any plans myself to climb onto the roof with a power drill, but because it was too fascinating that ordinary people in their spare time are busy building an invisible airborne network, without the rest of us even noticing.
What it is and how it works
When I started digging into what this equipment actually was, I realized the post had left out a few rather essential details about how you even get started. The post gave the impression that you pretty much just bought a gadget and tossed it in the attic. But reality requires a bit more work.
When you search for these devices online, you find a sea of different models. Some of them look like tiny walkie-talkies with a small screen, while others mostly resemble square radio cards for a computer, with just a stubby antenna sticking out. Common to the vast majority of them is that they cost a few tens of dollars and arrive directly from factories in China.
Software
But here is the first major hurdle that very few people think about: When the mail carrier drops off the little bubble mailer and you unpack your new radio card, it’s completely blank. It’s brain-dead. There is absolutely no software installed on it. Before it can make a peep, you have to find a perfectly ordinary USB cable – the kind you use to charge your headphones – and plug the radio card into your computer. Via a website, you simply have to install (flash) the software that brings the device to life yourself. It only takes a few minutes, but if you don’t know that, you’re just sitting there with a useless piece of electronics.
Once the card finally wakes up, we hit the next detail. The post mentioned that you could communicate without mobile phones. That’s a viewpoint requiring a vital nuance. It is entirely correct that the system works without the mobile network and cell towers. But the vast majority of these radio cards have no keyboard. They are mute. For you to write a message, you have to wirelessly connect your smartphone to the radio card via Bluetooth.
App or PC
You have to go into the App Store or Google Play and download a specific, free app for the purpose. You open the app on your phone, type your text, and hit send. The phone invisibly hands the message over to the radio card, which is lying on the windowsill or in your pocket, and then it’s the radio card doing the heavy lifting and shooting the signal out over the city roofs. In this setup, your luxurious phone has essentially just been demoted to a wireless keyboard and screen for the radio card.
If you don’t feel like being dependent on a smartphone app, there is a smart alternative, though. You can leave the radio card plugged into your desktop or laptop computer with the USB cable. Then you just open your web browser, type in a specific address, and voila – you have a complete control panel and chat window right there on your computer screen.
But if a genuine prepper or hardcore radio nerd is reading this, they would probably still shake their head at that setup. Because it doesn’t make much sense to base your crisis communication on a computer or a phone that dies when the blackout hits. And they are absolutely right.
That’s why the ultimate survival setup exists. If you invest a little extra in some special radio cards – for example, models with names like LilyGO T-Deck – you get a device that has a physical mini-keyboard and a screen built directly into the circuit board itself. They look a bit like the BlackBerry phones of the past.
In peacetime, it can sit in your PC while you nerd out with the settings. But the day society truly shuts down and the wall outlets die, you just pull the cable, attach a battery, and you have a 100 percent independent, handheld communication hub. No computers, no apps – just you and the radio waves.
Communication on the network
But how does the actual communication take place out there in the air? Here we have to kill another myth right away. Even though the small gadgets might look like walkie-talkies, forget all about pressing a button and talking. The system doesn’t support voices whatsoever. It is a hundred percent text-based. And we are not talking about modern messages where you can send long novels and funny pictures.
The technology is designed to shoot data incredibly far using minimal power, and the price for that range is speed and space. It’s much more akin to the very first SMS messages from the 90s. You typically only have around 200 characters available per message. Furthermore, radio waves move digitally heavily. When you hit send, it actually takes time – sometimes several seconds – before the message is chewed through and fired off, and the radio then needs a short pause to comply with the legislation on the open frequency band.
These small radio cards transmit on a very specific frequency called 868 MHz. In Denmark, this is an open radio band. It is the same part of the air that wireless weather stations, car keys, and burglar alarms use to send small, digital beeps to each other. It is an area of the air where anyone is allowed to be, as long as they don’t transmit with too much power.
To understand how the radios talk to each other on that frequency, imagine that the entire city is one big, pitch-black sports hall. That sports hall is the 868 MHz frequency. When your little radio card sends the text message you just wrote, it’s essentially standing in the middle of the dark shouting at the top of its lungs. Your signal physically flies right into the living room of everyone in the city who has a similar radio gadget turned on. Everyone in the dark sports hall can, in principle, hear the shout.
Encryption
If everyone in the dark sports hall can hear what my radio is shouting, does that mean the whole neighborhood can read over my shoulder? That was the next, rather pressing thought that arose. The post did promise that you could send encrypted messages, but how does that work in practice on an open radio frequency?
This is where the system really shows its strong side. Physically, your signal flies directly into everyone else’s radios, but the software in the phone or on the computer acts as an impenetrable, digital interpreter.
If you want to chat privately with a friend down the street, you create a closed channel. The software generates an extremely long and complicated mathematical code – a kind of secret dictionary that only your devices share.
When you type “Are you buying a coffee?” on your screen, the software uses the secret dictionary to turn the words into incomprehensible gibberish. For example, “XfyT19%Q!”. Your radio card stands up in the dark sports hall and shouts “XfyT19%Q!” at the top of its lungs.
All other radio cards in the city catch the sound. But because they lack your secret dictionary, their software simply concludes that the code is unreadable. The message is deleted in the background, without the owner ever getting a notification. Only your friend’s device can catch “XfyT19%Q!” and turn it back into a question about coffee. It is wiretap-proof communication right in the middle of a public square.
Repeaters
But even the most secure message is useless if it doesn’t arrive. The post encouraged people to offer their attics for so-called repeaters.
To understand what a repeater is, you first have to understand the very core of the network. It’s called a “mesh network,” which essentially just means the network is woven together like a mesh. Every single radio gadget, whether it’s in your pocket or plugged into your PC, automatically acts as a relay for others. If your radio picks up a message meant to go further away, it listens and automatically throws it forward.
But down at street level, buildings and trees block the signals. The range is limited. That’s where the dedicated repeaters come into the picture.
A repeater isn’t a large, expensive piece of telecom equipment. It is the exact same small, Chinese circuit board that you use down in the living room. The difference lies entirely in how you configure it, and where you place it.
If you take a radio card and hook it up to power up under the roof tiles on a high roof, the conditions change. Via the app on the phone, via the USB cable to your PC, or directly on the screen (if you have an advanced model like the LilyGO T-Deck), you can switch the card’s setting to “Repeater mode”.
In that mode, the unit turns off Bluetooth, the screen, and everything else that draws unnecessary power. Its only job is now to act as the city’s permanent echo. It sits high up without obstacles and listens. Every time it catches a weak signal from the street below, it repeats it with all its might. If you have a whole chain of these fixed repeaters standing on strategic attics, a small text message can bounce from roof to roof and travel several kilometers across the landscape.
So that was what the post was about: Building a shared infrastructure up high, so everyone down on the street could reach each other. But when I started looking closer at that plan, I realized that the very way the network is built is the subject of quite a bit of conflict within the nerd community.
Power Supply
The post made it sound like the easiest thing in the world: Toss a repeater up under the roof tiles, hook up a small solar panel, and let it take care of itself. But when you start calculating what it actually takes to build a stable infrastructure in an uninsulated, Nordic attic, reality is a bit different.
The short version is that small solar panels and standard batteries quickly fall short when the Danish winter brings weeks of darkness and freezing temperatures that kill electronics.
The solution that actually keeps the system running is incredibly simple. You build what in professional terms is called an Uninterruptible Power Supply – a UPS. You simply take a heavy, fully charged 12-volt battery, typically a leisure battery of the kind used in caravans, and place it next to the radio card. The battery is connected to a perfectly standard battery charger in the house’s wall outlet.
As long as society is functioning, the wall outlet pumps power into the battery. The day the power goes out in the entire district, the charger in the outlet naturally dies, but the repeater doesn’t notice that at all. It runs completely undisturbed directly off the large battery. And because these small radio cards use such a vanishingly small amount of power, a standard 12-volt battery can keep the network flying for over half a year, entirely without any power returning to the outlets. It is a highly robust, reliable, and long-lasting solution.
But when you have finally solved the power issue and gotten your radio card to survive both moisture and frost, you hit the next wall: Which language should the radio actually speak?
Meshtastic vs. Meshcore
The post I originally stumbled upon urged people to build repeaters for a network called Meshcore. But there is another, at least equally widespread system called Meshtastic. And here you suddenly find yourself in the middle of a classic format war. It’s reminiscent of the 1980s format war between Betamax and VHS videotapes, or today’s choice between Apple and Android, Windows and Linux. Two different standards trying to solve the same problem in their own ways.
Meshtastic is built on completely open code. It started around 2019 as a massive open-source project. Thousands of volunteer programmers sit and improve the system for free every single day, and there are already hundreds of thousands of devices out in the world. On the downside, the execution itself is more chaotic, and the network tends to drown in its own noise when too many users gather in the same city.
Meshtastic, being the original giant, wasn’t created for doomsday or crisis preparedness. It was created for people hiking in remote mountains, driving off-road in the desert, or attending the massive Burning Man festival in the US, where there are no cell towers. It was a system made for wide open spaces and scattered groups of people who just wanted to stay in touch. It’s brilliant if a group of friends is hiking in a desolate forest, because the messages just bounce back and forth between them. It’s called “flood routing”.
But when ordinary people in the cities started discovering the system, they brought the “hiker radio” into the concrete jungle. And so the anarchic system broke down when thousands of radios in a major city started shouting at each other all at once.
That is why the splinter group Meshcore emerged recently. They looked at the anarchic chaos and decided there was a need for hardcore structure. Some British nerds looked at the chaos and said: We can’t use a hiking network in a city. We have to build a system that behaves more like the professional telecom companies, where fixed towers control the traffic. This makes the network incredibly efficient at covering large geographic areas permanently without breaking down. Meshcore is built to route messages intelligently and efficiently around noise. That makes it strong in densely populated areas. But the code behind it is more closed, and the system is – at least right now – the smaller of the two.
But this is where things snap for the nerd community: Meshtastic is built by idealists, and everything is a hundred percent free and open for anyone to look at the code (open-source). The creators behind Meshcore, on the other hand, have chosen to keep central parts of their code secret, and they have introduced “freemium” models in their mobile app, where you can pay to avoid waiting for certain features. This has sparked an unforgiving hatred on the internet. The Meshtastic camp accuses Meshcore of stealing the free open-source spirit and turning it into a commercial milking machine, while the Meshcore camp shakes their heads at the fact that people would rather sit with an unstable, unusable city network than pay a flat ten-spot for a system that actually works on a large scale.
That is the conflict we are standing in the middle of. You have Meshtastic, which is the world’s largest, most widespread, but incredibly chaotic system. And then you have Meshcore, which technically is more streamlined for city use, but which almost no one knows about yet.
In principle, the two systems can easily coexist in the future, just like petrol and diesel cars do on the roads. Both formats have their obvious strengths and weaknesses.
But for the average beginner, this means facing a defining choice before even getting started. Should you bet on the system that is perhaps technically sharpest for cities, but where there are fewer users? Or should you choose the slightly noisier system where the vast majority of others already are?
And here one might naturally be tempted to think the perfectly logical thought: Why not just put two radios up next to each other and run both networks at the same time? But here physics trips us up once again. Since both systems transmit on the exact same radio frequency, two repeaters with their own languages will end up completely drowning each other out and interfering when they try to shout in the sports hall at the same time. You simply have to make a choice and opt out of the other.
Who is building it?
Once I finally wrapped my head around the sports hall, the batteries, and the bitter format war, the next inevitable question hit me. Who on earth spends their evenings, weekends, and pocket money building all of this in secret?
I initially had a slight prejudice that it was probably primarily doomsday types with Rambo knives and camouflage nets. But when you understand what the network can actually do and offer, a picture emerges of a fascinating alliance of vastly different subcultures that normally don’t have much to do with each other.
The most visible group is indeed the preparedness folks, or the preppers. For them, it’s about pure and simple security. They look at the unrest in the world and think: What do we do when we can’t call 911, and we can’t get hold of our kids? For them, these small radio cards are the ultimate insurance policy; a digital life preserver when the system fails.
Then there are the privacy fundamentalists. They are driven by a deep ideological opposition to surveillance capitalism. They loathe the idea that tech giants or the government can look over their shoulder every time they send a message. For them, a network that no one owns and that no one can log centrally is the very Holy Grail. It’s an invisible, digital rebellion against the system.
But the group I could personally identify with the most were the gear nerds and nostalgia riders. This is where the threads are pulled straight back to my teenage bedroom in the early 90s. Back then, a bunch of my buddies and I lay in our respective beds at night with stationary walkie-talkies that received signals from giant antennas our fathers had bolted to the gables of the houses, and we talked for hours deep into the night. While the German TV channels flickered in the background, we were hanging out in the open space of the airwaves where everyone could listen in. Long before the internet even existed, hours were spent on free, airborne conversation about everything from what we had just seen on TV to local gossip and backbiting – because we all knew who had walkie-equipment and who didn’t.
The Walkie-Talkie Comparison
But here the comparison also comes to an abrupt halt. Because even though the nostalgia lives on, the analog walkie-talkie loses ground on two absolutely crucial points when we talk about real crisis preparedness: Power and range.
A classic walkie-talkie is built to send a human voice through the airwaves, and that requires raw, physical muscle power. If the power goes out for several days, a traditional radio will quickly drain even a solid car battery once you’ve pressed the transmission button down enough times.
The mesh network, on the other hand, operates with tiny, digital impulses that only last fractions of a second. This means the small device in your pocket can be kept alive for weeks on a single, cheap powerbank.
Then there’s the noise. We all remember the analog static when the signal got weak. A voice quickly disappears into the dark if the distance is too great or the terrain is difficult.
The mesh network, on the other hand, is all-or-nothing. It cleans up the digital noise itself, checks for errors, and intelligently routes the message forward via the other repeaters in the attics. It is the difference between standing and shouting out into a dark forest hoping someone hears you, and sending a digital courier off with a coded letter that patiently jumps from roof to roof until it reaches the recipient.
Although the technology has shifted from an analog shouting match to digital intelligence, the driving force behind it all is often the same. Exactly that curiosity about how far a signal can reach is alive and well, along with the urge to tinker with electronics.
For many of the grown men who buy Chinese circuit boards today, these small devices have simply become the newest piece of adult Lego. It’s not necessarily about preparing for World War III. It’s more about sitting hunched over the workbench in the glow of an architect lamp, soldering iron in hand, building some sort of Rube Goldberg contraption and getting a massive kick out of the fact that it actually works.
The dark side of the invisible web
But as innocent as it might sound to play with adult Lego, the perspective becomes equally dark when you flip the coin. What happens when criminals discover an independent, completely blacked-out, and encrypted network?
On paper, it sounds like the ultimate dream for terror cells and drug syndicates. No telecom companies to hand over logs to the police, and nothing that can be traced. But reality is fortunately a bit more clunky. For heavy, organized criminals, the technology is simply too slow and too unstable. They would much rather pay top dollar for illegal crypto phones that run lightning fast and flawlessly on the telecom companies’ existing highway.
But there is one place where the technology seriously has the potential to give the authorities cold sweats: Behind bars.
The Prison and Probation Service spends massive resources on blocking and killing regular mobile signals inside prisons with advanced jamming equipment. But what about a tiny, mute circuit board the size of a matchbox, smuggled into a cell?
It transmits on a completely different, low frequency that often flies entirely under the radar. If an inmate has such a gadget hidden under the mattress, and an accomplice has set up an invisible repeater in a tree a few hundred meters outside the prison wall, a massive, invisible security hole can emerge. No towers register it, no one can intercept the mathematical gibberish, and the prison’s jammers might never detect it.
The technology thus spans the entire spectrum. From cozy walkie-talkie nostalgia to the possibility of a totally blacked-out communication tool for the country’s inmates.
The Fragile Society
When you take a step back from the soldering irons, the heavy car batteries, and the security holes in prisons, you are left with the big, overarching question. What does it actually say about us that thousands of completely ordinary people suddenly spend their free time building an alternative, invisible internet up under the roof tiles?
The way I see it, it says everything about the inherent fragility we have built into modern society. We have created a hyper-efficient, digital everyday life where everything runs on rails. We have no cash, no landline phones, and all our knowledge and communication resides in an invisible “cloud” that is realistically just gigantic server parks powered by massive amounts of electricity and vulnerable cables in the ground. We have sacrificed our resilience on the altar of efficiency and convenience.
When people buy bare Chinese circuit boards and hide them in the attic, it is actually a physical manifestation of a creeping distrust. It is not necessarily a tin-foil-hat distrust of the government, but rather a deep distrust of the infrastructure itself. It is a quiet realization that if a massive hacker attack, a massive blackout, or an accident that severs the wrong fiber cable occurs, we are completely, paralyzingly isolated from each other within minutes.
Building your own network is taking back a tiny sliver of control. It is the ultimate, modern form of self-reliance.
To do or not to do ?
But as for myself? When I finally reached the bottom of the story about the secret, airborne network, I calmly left my payment card in my pocket. At least for now.
The idea is incredibly fascinating, but when everyday life hits, it is simply a bit too much hassle for me personally to bother diving into it. The thought of having to battle freezing attics, monitor the power on a heavy camping battery, and pick a side in a nerdy format war to solve a problem that might never ever arise… it is ultimately too big of a mouthful. I safely leave the attic work and the soldering irons to those who are truly passionate about it.
However, I cannot rule out that at some point I might “accidentally” invest in a LilyGO T-Deck for my computer – just to see if anything is actually happening in the radio waves, which I can then follow along with a bit. Then I’ll have it ready if the world does collapse, and then the power supply issue will just have to wait until that happens.